If using one microphone is great, two must be twice as good, right? Sometimes. 🙂
Some of the best acoustic guitar tones I’ve ever gotten have been with two microphones, this is sometimes referred to as stereo mic placement (although two microphones doesn’t always mean it’s technically “stereo,” but that’s for another day).
As with most things, if there stands to be a bigger benefit (better guitar tone), there are also greater risks (phase issues).
One of the main reasons to use some sort of stereo mic technique is to capture a much wider signal. Rather than a guitar sound that’s fairly one-dimensional, using two microphones lets you capture more realistic, wide-sounding guitar. This is especially good for songs that have very little instrumentation. Full band productions typically don’t benefit from stereo-mic’d acoustic guitar, mainly because you just can’t hear it in the mix.
There are lots of ways to stereo-mic acoustic guitar — XY, Blumlein, Mid-Side, ORTF, Spaced Pair — to name a few. Each of these has its own benefit and drawbacks, and some have a “wider” sound than others. They all, however, give a wider, more realistic sound to the guitar. Think about it, we listen with two ears, it makes sense that two microphones would capture a more realistic sound.
Whenever you use more than one microphone on a source, you introduce the issue of phasing. Simply put, when a single signal reaches two microphones at different points in time, the resulting sound can be thin or hollow. The slight difference in time (or phase) causes certain frequencies to cancel out.
The key to this is two-fold. First, observe the 3:1 Rule. If the microphones are too close together, phasing WILL happen…and you’ll wish you had just stuck with one microphone.
The second way to combat this is to listen in mono. When you’re placing the microphones, listen to them in mono, NOT stereo. Stereo will sound awesome, but it won’t let you know if there are any phase issues. Listening in mono will quickly point out any problems. If the signal sounds thin, or maybe even boomy, or boxy, or hollow, try moving one of the microphones a few inches. Listen as you move it. Once it sounds good again, THAT’S your placement.
So, what do you think? Leave a comment below and let us know if you stereo-mic acoustic guitar (and why).
If you want to learn all about recording acoustic guitar, join me for the 4-week class, starting this Thursday. Limited spaces available. Click here to check it out.